I figured that CSS sheets on the list you see when you click the icon are arranged by which loads first, since when I add my CSS sheet it appears the last, but after I refresh the page, it appears the first and is loaded the first — and this is the problem, as that sheet is no longer loaded last and is thus over-ridden by page default sheets. (Which I need to have enabled in order for page to display properly). I suppose that this would be a good addition for those of us who have barely basic knowledge of what CSS is.